Method and apparatus for oiling sheet metal



March 9, 1948. G. A. KAUFMAN METHQD AND APPARATUS FOB. OILING SHEET METAL Fil d Nov. 27. 1944 2 Sheets-Sheei 1 INVENTOR George/4. KaufmanMarch 9, 1948. G, A, KAUFMAN 2,437,606 j THOD AND APPARATUS FOR OILINGSHEET METAL I 2 Sheets-Sheet 2 Filed Nov. 27, 1944 INVENTOR fi e/99A.Kaufman MW 44 M111,

Patented Mar. 9, i948 METHOD AND APPARATUS FOR OILING SHEET METAL GeorgeA. Kaufman,

Jones & Laughlin Aliquippa, Pa.,

Steel Corporation,

assignor to Pittsburgh, Pa., a corporation of Pennsylvania ApplicationNovember 2'7,

3 Claims. (01. 117-93) This invention relates to the oiling of sheetmetal, such as tinplate, in continuous strip, and more particularly to amethod and apparatus for applying a very thin film of oil toelectrotinned strip.

An object of the invention is to provide a method and apparatus forapplying to sheet metal, such as tinplate, a film of oil of uniformthickness sufficient to protect the metal during storage and shipment,but not so thick as to interfere with subsequent processing.

In the manufacture of tinplate, for example, it is highly desirable tohave a thin film of oil on the surface of the plate when it is packagedfor shipment, for several reasons. If the plate is packaged withoutoiling and is stored for a period of time prior to use, it may rustinspots, particularly if stored in damp or humid surroundings. If theplate is packaged without oiling and roughly handled in shipment theindividual sheets or plates may rub upon one another sufficiently toproduce black spots on the coating-a form of tin oXide objectionable tothe user. And finally, unoiled sheets, after having been stacked, tendto stick together and so jam the automatic feeding machines used by canmakers.

For certain applications, however, the thickness of this oil film mustbe kept to a minimum. Light weight tinplate-that is, plate with a thintin coating-is quite generally lacquered or enamelled by the can makerfor a number of types of cans, and this lacquer or enamel does notadhere well if an appreciable amount of oil is found on the tinplate.Thus the tinplate producer encounters difficulty in applying enough oilto protect the plate in shipment but not so much as to impair lacqueradhesion.

This problem is most acute with electrolytically tinned sheets. Thegreat bulk of electrolytic tinplate is made with thin tin coatings, onthe order of /2 to lbs. of tin per base box of plate. A base box oftinplate contains sheets totalling 217.78 sq. ft. of surface, one side.Nearly all of this product is lacquered by the can maker. Although oilis widely used in the brightening stage of the manufacture ofelectrolytic tinplate, the film left on the plate is generally not theweight and type desired by the user and therefore the finished platemust be oiled as a separate step in the production process. It is withthis step in the manufacture of tinplate that my invention is concerned.

Electrolytic tinplate is all produced as continuous strip, and is onlysheared to sheets as the last step before sorting and packaging. It is 6therefore highly desirable 1944, Serial No. 565,315

to apply the oil to the strip. Because of this, the methods ofcontrolling the oil thickness employed for hot dip tinplate, which isproduced commercially as separate sheets-are not readily applicable, andConventional as oiling by spraying or dipping the sheet, or dippingfollowed by branning to remove excess oil, have been adapted tocontinuous strip but have been found incapable of proclosing a uniformoil film of the desired thinness. The method has been reversed, and afixed quantity of oil added to the bran, through which the strip is thenrun, but also without the desired result. Other processes have beentried, but it can be said of the oil films they deposit, that thoseproviding protection impair lacquer adhesion, and those which do notimpair lacquer adhesion do not provide sufficient protection. Prior tomy invention, no method of oiling electrolytically tinned strip wasknown which deposited a film sufficient to provide protection in storageand transit but thin enough not to impair lacquer adhesion.

In the application of Robert A. Woofter and Robert H. Smith, Serial No.565,314, filed November 27, 1944, now Patent No. 2,429,862, issuedOctober 28,1947, there is disclosed a continuous process for oilingstrip which produces an exceedingly t in but continuous film of oil onthe metal surface, sufficient to provide protection in storage andtransit, and not detrimental to lacquer adhesion. That process comprisesatomizing oil with air to form a mist of oil particles suspended in air,heating such a mist to vaporize the oil particles, and finally causingthe oil vapor so formed to condense on the surfaces of the this mannerthey can deposit on the film so thin that only .1 of a gram of oil issufficient for a base box, or one pound of oil covers 2,000,000 sq. ft.of surface; such a film has been found to have no detriment-a1 effect onThis film, moreover, is so uniform, and covers the surface of thetinplate so completely that it provides adequate protection to theplate. Such tinplate, with a uniformly distributed oil film of thisthickness, is a new article of manufacture, never before available.

The present invention is an improvement over the Woofter and Smithinvention. According to my invention, the condensation of the oil vaporon the sheet metal is made more efficient by carrying out thecondensation in an electrostatic field. By this means the molecules ofoil vapor are charged with a high potential with recontinuous tialdifference is created between the molecules of the vapor and the strip,the time necessary for the vapor to be in contact with the stripFurthermore, the condenon the strip is so com- In the accompanyingdrawings which illustrate a preferred embodiment of my invention partsbeing shown in elevation and Figure 2 is a vertical section through oneof the spraying devices.

My process is most conveniently carried out at a point in the tin linejust before the final coiler, where the strip can be made to runvertically. As shown in Figure l,

8 to a coiler 9. In traveling upwardly between the rollers 5 and E, thestrip passes first through a vaporizing chamber it! On each side of thestrip and located in the vaporizing chamber is a row of atomizingnozzles a stream of oil mist ticles suspended in air. The may not beheated; in the case of an oil such as palm oil or paraiiin which is asolid at ordinary temperatures sufficient heat to liquify the oil is, ofcourse, essential. It is generally desirable to heat the air to insureits dryness but neither the oil nor air is heated to a temperature muchhigher than 200 F. Inany case after passing through the spray nozzlesE5, the mist or oil-air mixture is probably cooled to a temperature nearroom temperature by the expansion. The nozzles it are preferably placedabout 6 to 7 inches from the strip and the streams of oil mist aredirected as shown bythe reference numeral I6 and impinge first upon thebafiies I! and then rebound to baffles are directed toward the strippinge on the strip.

In order to accelerate condensation of the oil vapors on the strip, Iarrange a pair of fine wires 49 in the bottom of the hood M on each sideof the strip 2. The Wires 40 are connected to the potential is applied,charged in the electrostatic field and all, if not all, the vapor iscaused to condense on the strip.

The thickness of oil film deposited is controlled both by the amount ofoil fed to the spray determined by the operating conditions of the istaken up or let out For a uniform oil film it is necessary that the oilsupply the tin line. drive itself,

made by a rheostat in the D. 0. power supply satisfactory with the wiresabout 1 strip on each side. up therefore has a strength of between10,060 volts. per inch.

The amount of heat necessary to introduce into the baiiies 5'. and i3 isquite easily determined from observation. If the bafiies are observed tobe wet, not all the oil is being vaporized, and more heat is required.If the bafiies are too hot, some oil will burn, producing smoke whichtected. For cottonseed oil, we bafilc, if electrically watts per inchwidth of the heaters the electrical is easily de find that each heated,requires about of strip. The temperature may be controlled bycontrolling power input, or by he spray. At higher air pressures moreair is blown upon the heaters, thus cooling them.

A preferred type of spray or atomizer is illustrated in Figure 2, thisfigure being a vertical cross section through one of the spray heads. Anumber of spray heads are arranged on each side of the strip so as tocover the width of the be sprayed. A block or housing 20 is formed Witha trough 2. which receives oil flowing through pipes 22, 23 and The oilflows through an opening 25 in the pipe 24 into the trough 2i and theoverflow passes over a dam 26 into a sump or return 2'! from which it isre- (not shown). The housin an electrical turned to a pump may beprovided, if desired, with heater 28 for heating 29 are mounted on ashaft 30, the shaft being driven directly or indirectly from the drivingmeans for the strip so that the shaft and wheels 29 rotate in accordancewith the speed of passage of the strip through the apparatus. A nozzle3! is located above each wheel 29. The nozzle is provided with a passage32 controlled by a valve 33, the passage communicating with a pipe 34which supplies air. Adjacent the outlet of the air passage 32 is a plate35 which directs the air downwardly past an atomizing tube 35 formed inthe nozzle. The tube 36 is located adjacent a shoulder 31.

As the wheel 22 is rotated, it picks up a film of oil from the oil inthe trough 2i and raises it to a point adjacent the tube 36 where thefilm of oil is scraped off by the shoulder 31 and flows through the tube35 in a very fine stream. The oil issuing from the tube 36 is atomizedby the air flowing through the passage 38 forming a mist of oil dropletsor particles suspended in air. This stream of mist is directed againstthe heated baflles l1 and is as previously described and the mist iscondensed on the strip 2. In the embodiment shown, the air nozzles 31and discs 29 are spaced about 1 inch apart over the width of the strip.This spray produces a very uniform oil mist because the rotating discs29 bring up oil to the air stream at a rate varying only with the speedof rotation of the shaft 30. The amount of oil atomized is thus easilycontrolled by controlling the speed of rotation of the shaft.

The pressure of air required is low, 2 to 4 lbs. being satisfactory,except when the air flow is also used to control the baliie temperatureas previously mentioned. Under such conditions, pressures up to 12 lbs.have been employed, with satisfactory results.

The type of oil used depends, of course, on the customers requirements.Palm oil is occasionally used by me for electrolytic plate, butcottonseed oil is more generally employed. For some purposes a syntheticcompound such as dibutyl sebacate is more desirable. Parafiin oil, andhydrogenated fish oil have also been used occasionally. It is understoodthat my process is capable of utilizing any oil required and is notlimited as to type of lubricant.

It will be understood also that my process is not confined to tinplate,but is applicable to any metal plate or strip which requires a thin,uniform film of oil.

The invention is not limited to the preferred embodiment which has beengiven merely for purposes of illustration, but may be otherwise embodiedor practiced within the scope of the following claims.

I claim:

1. The method of continuously applying a thin, uniform film of oil toboth sides of continuous strip metal comprising moving the stripvertical- 1y, continuously supplying oil at a predetermined rate to aplurality of air streams disposed on both sides of the strip, atomizingthe oil with the air to form a mist of oil particles suspended in air,

plurality of heated surfaces interposed between the air streams andstrip in such manner that no oil particles impinge on the strip,maintaining the heated surfaces at a temperature sufficient to vaporizethe oil particles, and charging the molecules of the vapor to a highpotential with respect to the strip by causing them to pass through anelectrostatic field having a strength between 8000 and 10,000 volts perinch, whereby said molecules are attracted toward the strip andcondensed thereon.

chamber, a cooling chamber, means for passing the sheet metalcontinuously through the vaporizing chamber and cooling chamber, meansin the vaporizing chamber for atomizing oil with air to form a mist ofoil particles suspended in air, at least one bafile interposed betweensaid atomizing means and the strip, and heating means for maintainingthe baiiic at a temperature sufficient to vaporize the oil particles,the baffle being arranged so that no oil particles can impinge on thesheet metal, and means for charging the molecules of vapor to a highpotential with respect to the strip, whereby the molecules are attractedtoward the strip and condensed thereon.

3. Apparatus for applying a uniform film of oil to sheet metal, whichcomprises a vaporizing chamber, a cooling chamber, means for passing thesheet metal continuously through the vaporizing chamber and coolingchamber, means in the vaporizing chamber for atomizing oil with air toform a mist of oil particles suspended in air, the atomizing meanscomprising a plurality of nozzles each having an air passage and a wheelasso ciated with each air nozzle and adapted upon rotation to carry afilm of oil adjacent the outlet of the air passage and be atomized, atleast one baiiie interposed between said atomizing means and the strip,and heating means for maintaining the baffle at a temperature sufficientto vaporize the oil particles, the baille being arranged so that impingeon the sheet metal, and means for charging the molecules of vapor to ahigh potential with respect to the strip, whereby the molecules areattracted toward the strip and condensed thereon.

GEORGE A. KAUFMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS 2,334,648 Ransburg NOV. 16, 1943

